Healthy men (n=22) and women (n=24) slept in the test room from 23:00 to 07:00 h on two nights spaced over a week. These first two sessions were used to evaluate the effects of nocturnal exposure on cardiac endpoints. Half the subjects selected at random were exposed on the first test night, and then sham exposed on the second night; the remaining subjects participated in the reverse order. One week later, the probands returned for a further two nights to test the sleep parameters.
|Chamber||each subject slept overnight in a sound-attenuated and air-conditioned exposure test room (a cube about 2.4 m on each side)|
|Setup||Merrit-type horizontal and vertical concentric coil system surrounding the exposure chamber; one axis of the field was phase-shifted 90°|
|Sham exposure||A sham exposure was conducted.|
|magnetic flux density||28.3 µT||-||-||-||-|
Regarding the heart rate variability, under exposure conditions, male probands showed a decrease in the power spectrum (respective low frequency) over the entire night compared to sham exposure conditions. No field-related effects were found in women.
Regarding the sleep, exposed women showed a decreased percentage of time in REM sleep compared to sham exposed women. Additionally, the total amount of time the women remained asleep and sleep efficiency was reduced compared to the sham exposed women. No field-related effects were found in men.
The authors conclude that gender-specific effects seen in this study in older volunteers, replicate the results of previous studies with younger men and women (Sastre, 1998; Sait, 1999; Graham, 1996).